Carbon dioxide (CO2) separation from diverse sources such as natural gas (mainly CH4), flue gas (mainly N2), and syngas (mainly H2) is vital to mitigate its aversive role in global warming. Most of the commercially available membranes have been designed from polymeric materials due to the simple membrane preparation with numerous polymers desirable performance and availability. In this context, thiol-ene chemistry has been widely applied for designing different polymeric membranes due to the fast reaction kinetics and the versatile selection of thiol and ene functionalities. Moreover, thiol-ene reactions offer a promising candidate for large-scale CO2 separations because of their viability with the presence of oxygen and fabricating polymeric materials with fast and high conversions. Thus, this study addresses two strategies to improve the CO2 separation performance of photocurable thiol-ene network membranes. In the first strategy, thiol-ene photopolymerization will be applied to design amorphous poly(ethylene glycol) (PEG)-based elastomeric networks for CO2 separation. The starting material, a combination of a non-PEG ene and a non-PEG thiol, was gradually modified with a PEG thiol to place PEG moieties in the backbones while maintaining 1:1 thiol-ene stoichiometry. Furthermore, the PEG units will be also placed in the dangling chains using modified thiols with acrylate. This study aims to determine the minimum content of PEG units needed for achieving the highest CO2 solubility, with different PEG placements (in the backbone and dangling chain), to realize the structure effect on gas transport properties. In addition to the PEG-incorporation strategy, zeolite 4A particles with different contents will be incorporated into a photopolymerizable glassy thiol-ene network to design mixed matrix membranes (MMMs) to overcome the trade-off between gas selectivity and permeability (known as the Robeson upper-bound limit) faced by most polymeric membranes. Zeolites are widely used in CO2 separation due to their tailorable cavities and pore sizes, high surface area, hydrothermal stability, low-cost, and high accessibility.

Tailored photopolymerizable thiol-ene network membranes for advanced CO2 separation

ACS Spring Meeting 2021

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